Indomethacin is known as a non-steroid antiphlogistic having an excellent antiphlogistic effect. Indomethacin is believed to have an antiphlogistic function 85 times that of phenylbutazone (rat granuloma suppressive function), an anodyne function of 75 times that of aspirin (Rat Randall-Selitto's method) and an antipyretic function of 20 times that of phenylbutazone (pyrogen-febrile rabbit). Accordingly, it has been widely used hitherto, for treating symptoms such as chronic rheumatoid arthritis, osteoarthritis, spondylosis deformans or periarthritis humeroscapularis, etc., and moreover inflammation and pain after surgery or an external injury.
Indomethacin is used generally orally or as a suppository.
Although indomethacin has a strong therapeutic effect, it causes side effects such as gastro-intestinal trouble, and, therefore, it is especially restricted for peptic ulcer patients. Recently, in order to reduce such side effects, ointments containing indomethacin has been proposed, which are applied directly to the affected part to cure by localized absorption of the indomethacin through the skin. According to this method, sufficient reduction of side effects can be expected and the above described therapeutic effects of indomethacin can be safely exhibited.
However, even though ointments have the above described advantage, they have the disadvantage that the correct dosage to the body is difficult to control, because the ointment applied to the surface of the body is wiped away by clothes and, further, the release rate of the indomethacin from the ointment is not definite. Further, as a result of wiping away by clothes, clothes are soiled.
Recently, as a means for solving these various disadvantages caused by application of the ointment, a product which is obtained by mixing a drug such as a corticosteroid with a pressure-sensitive adhesive composition and applying the mixture to a substrate to form a coated film has been proposed.
In products containing corticosteroids, the therapeutic effect can be attained only by contacting the steroids with the skin, because of their characteristics on the clinical use.
On the contrary, in case of indomethacin, the desired effect cannot be attained by only forming a pressure-sensitive adhesive layer containing indomethacin to a substrate, because it is necessary for indomethacin to penetrate deeply under the skin in order to obtain the therapeutic effect.